The long-term trend of consolidation among U.S. health plans has raised providers' concerns that the concentration of health plan markets can depress their prices. Although this study confirmed that, it also revealed a more complex picture.

First, these researchers found that 64 percent of hospitals operate in markets where health plans are not very concentrated, and only 7 percent are in markets that are dominated by a few health plans. Second, they found that in most markets, hospital market concentration exceeds health plan concentration. Third, the study confirmed earlier studies showing that greater hospital market concentration leads to higher hospital prices. Fourth, the study found that hospital prices in the most concentrated health plan markets are approximately 15 percent lower than in more competitive health plan markets.

Overall, the study found that more concentrated health plan markets can counteract the price-increasing effects of concentrated hospital markets, and that—contrary to conventional wisdom—increased health plan concentration benefits consumers through lower hospital prices, as long as health plan markets remain competitive. These findings also suggest that consumers would benefit from policies that maintained competition in hospital markets or that would restore competition to hospital markets that are uncompetitive.